Method for Forming an U-shaped Metal Frame

ABSTRACT

A method for forming an U-shaped metal frame includes a preparing means: bend forming a straight tube in a continuous curve shape to be a billet including a spaced section and a first and a second side segments twisted toward opposite directions individually; a forming means: placing the billet into a cavity of a forming mold, closing two ends of the billet, and feeding a high-pressure fluid into the billet; a cutting means: cutting the billet into the first and the second pipes, the first pipe including a first connecting portion formed in a first cut position thereof, the second pipe including a second connecting portion formed in a second cut position thereof; a connecting means: twisting the first side segment and the second side segment toward the same direction, and connecting the first connecting portion and the second connecting portion together to obtain the U-shaped metal frame.

BACKGROUND OF THE PRESENT INVENTION

1. Field of Invention

The present invention relates to a method for forming an U-shaped metalframe that can simplify its forming process.

2. Description of Related Arts

U-shaped frame, such as a horizontal main frame, an engine holder, orseat support of a car, made of a metal tube is used in vehicle andaerospace industries to connect with other parts.

Referring to FIGS. 1 and 2, an U-shaped metal frame 10 is used in a seatsupport of a car and includes a spaced section 11 and a first and asecond side segments 12, 13, wherein the spaced section 11 includes alarger-diameter expanding portion 111 disposed on a central portionthereof, and the first and the second side segments 12, 13 include afirst and a second recessed parts 121, 131 mounted on one sides thereofrespectively, the first and second recessed parts 121, 131 include curveor convex cross section formed thereon individually. During theprocesses of forming the metal frame 10, two plates are provided to bepunched by a punching die and then welded together to form the spacedsection 11, and two straight tubes are provided to be punched by anotherpunching die to form the first and the second side segments 12, 13,thereafter the first and the second side segments 12, 13 are weldedtogether to form the metal frame 10. However, such a punching method hasthe following disadvantages:

1. Plural punching dies are used to punch the spaced section 11, thefirst and the second side segments 12, 13 individually, and then thespaced section 11, the first and the second side segments 12, 13 arewelded together, thus increasing die cost and having complicate formingprocesses.

2. A number of connecting positions of the spaced section 11, the firstand the second side segments 12, 13 are welded together, increasingproduction cost.

3. The spaced section 11, the first and the second side segments 12, 13are welded together after being punched, lowering rigidity and strengthof the metal frame.

Referring to FIGS. 1 and 3, the metal frame 10 is made by using a fluidforming method, wherein a straight tube is bent by a tube bendingmachine to form a U shape, the U-shaped tube is placed into a cavity ofa forming mold, and then a punching head is used to close two ends ofthe U-shaped tube, a high-pressure fluid is fed into the U-shaped tubeso that the U-shaped tube is inflated in the cavity to form a concave orconvex cross section on a first and a second recessed parts 121, 131 ofthe first and the second side segments 12, 13 individually, however, ifa low-cost mold is applied to form the first and the second recessedparts 121, 131, the first and the second side segments 12, 13 are notremoved from the mold easily to form the first and second recessed parts121, 131, accordingly another molds have to be used to form the concaveor convex cross section on the first and the second recessed parts 121,131, increasing production cost and having tedious forming processes.

The present invention has arisen to mitigate and/or obviate theafore-described disadvantages.

SUMMARY OF THE PRESENT INVENTION

The primary object of the present invention is to provide a method forforming an U-shaped metal frame that can simplify its forming process.

Secondary object of the present invention is to provide a method forforming a U-shaped metal frame that can lower production cost.

Further object of the present invention is to provide a method forforming an U-shaped metal frame that can form a concave or convex crosssection on the spaced section and the first and the second side segmentsindividually to save mold cost.

Another object of the present invention is to provide a method forforming an U-shaped metal frame that can decrease connecting portions ofthe U-shaped metal frame to enhance strength and smooth surface.

In accordance with the present invention, there is provided a method forforming an U-shaped metal frame which includes

a preparing means: bend forming a straight tube in a continuous curveshape to be a billet of the metal frame, and the billet including aspaced section and a first and a second side segments twisted towardopposite directions individually;

a forming means: placing the billet of the metal frame into a cavity ofa forming mold, and closing two ends of the billet, and then feeding ahigh-pressure fluid into the billet so that a concave or convex crosssection is formed on the billet;

a cutting means: cutting the billet into the first and the second pipes,and the first pipe including a first connecting portion formed in afirst cut position thereof, and the second pipe including a secondconnecting portion formed in a second cut position thereof;

a connecting means: twisting the first side segment of the first pipeand the second side segment of the second pipe toward the samedirection, and connecting the first connecting portion of the first pipeand the second connecting portion of the second pipe together to obtainthe U-shaped metal frame.

The present invention will become more obvious from the followingdescription when taken in connection with the accompanying drawings,which show, for purpose of illustrations only, the preferred embodimentin accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a conventional U-shaped metalframe;

FIG. 2 is a process for forming the conventional U-shaped metal frame;

FIG. 3 is another process for forming the conventional U-shaped metalframe;

FIG. 4 is a process for forming an U-shaped metal frame according to afirst embodiment of the present invention;

FIG. 5 is a cross sectional view showing a preparing means of a methodfor forming the U-shaped metal frame according to the first embodimentof the present invention;

FIG. 6 is a cross sectional view showing a forming means of the methodfor forming the U-shaped metal frame according to the first embodimentof the present invention;

FIG. 7 is a cross sectional view showing a fluid forming of a formingmeans of the method for forming the U-shaped metal frame according tothe first embodiment of the present invention;

FIG. 8 is a cross sectional view showing a heat treating of a formingmeans of the method for forming the U-shaped metal frame according tothe first embodiment of the present invention;

FIG. 9 is a cross sectional view showing a cutting means of the methodfor forming the U-shaped metal frame according to the first embodimentof the present invention;

FIG. 10 is a cross sectional view showing a connecting means of themethod for forming the U-shaped metal frame according to the firstembodiment of the present invention;

FIG. 11-1 is a side plan view showing the connecting means of the methodfor forming the U-shaped metal frame according to the first embodimentof the present invention;

FIG. 11-2 is another side plan view showing the connecting means of themethod for forming the U-shaped metal frame according to the firstembodiment of the present invention;

FIG. 12-1 is another side plan view showing the connecting means of themethod for forming the U-shaped metal frame according to the firstembodiment of the present invention;

FIG. 12-2 is another side plan view showing the connecting means of themethod for forming the U-shaped metal frame according to the firstembodiment of the present invention;

FIG. 12-3 is another side plan view showing the connecting means of themethod for forming the U-shaped metal frame according to the firstembodiment of the present invention;

FIG. 13 is a cross sectional view showing a preparing and a formingmeans of a method for forming the U-shaped metal frame according to asecond embodiment of the present invention;

FIG. 14 is a cross sectional view showing a cutting means of the methodfor forming the U-shaped metal frame according to the second embodimentof the present invention;

FIG. 15 is a cross sectional view showing a connecting means of themethod for forming the U-shaped metal frame according to the secondembodiment of the present invention;

FIG. 16 is a cross sectional view showing a preparing means of a methodfor forming the U-shaped metal frame according to a third embodiment ofthe present invention;

FIG. 17 is a cross sectional view showing a forming means of a methodfor forming the U-shaped metal frame according to the third embodimentof the present invention;

FIG. 18 is a cross sectional view showing a cutting means of the methodfor forming the U-shaped metal frame according to the third embodimentof the present invention;

FIG. 19 is a cross sectional view showing a connecting means of themethod for forming the U-shaped metal frame according to the thirdembodiment of the present invention;

FIG. 20 is a cross sectional view showing a preparing means of a methodfor forming the U-shaped metal frame according to a fourth embodiment ofthe present invention;

FIG. 21 is a cross sectional view showing a forming means of a methodfor forming the U-shaped metal frame according to the fourth embodimentof the present invention;

FIG. 22 is a cross sectional view showing a cutting means of the methodfor forming the U-shaped metal frame according to the fourth embodimentof the present invention;

FIG. 23 is a cross sectional view showing a connecting means of themethod for forming the U-shaped metal frame according to the fourthembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 4 and 5, a method for forming an U-shaped metal frame20 in accordance with a first embodiment of the present inventioncomprises the step of providing a metal straight tube in a preparingmeans, wherein the straight tube is bend formed in a continuous curveshape to be a billet of the metal frame 20, the billet includes a spacedsection 201 and a first and a second side segments 202, 203 twistedtoward opposite directions individually. In this embodiment, thestraight tube is bent by a tube bending machine to form a continuouscurve shape. As shown in FIGS. 4, 6 and 7, the billet is placed into acavity of a forming mold, and the forming mold is split along a curvedaxial line of the billet, the cavity includes two punching headsdisposed on two sides thereof respectively to close two ends of thebillet, and a high-pressure fluid is fed into the billet so that thebillet is inflated in the cavity to form a concave or convex crosssection on the spaced section 201 and the first and the second sidesegments 202, 203 individually, wherein the spaced section 201 of thebillet includes an expanding portion 204 formed thereon, and the firstside segment 202 includes a first recessed part 205 formed thereon, andthe second side segment 203 includes a second recessed part 206 formedthereon. In this embodiment, the concave or convex cross section isformed on the spaced section 201 by using a fluid forming or a heattreating method. As illustrated in FIG. 7, the fluid forming methodincludes placing the billet of the metal frame 20 into the cavity of theforming mold, and the punching heads of the cavity are used to close thetwo ends of the billet, the high-pressure fluid is fed into the billetdirectly so that the billet of the metal frame 20 is inflated in thecavity by using a pressure of the high-pressure fluid, and then theconcave or convex cross section is formed on the billet. With referenceto FIG. 8, the heat treating method includes pre-heating the billet ofthe metal frame 20 to a suitable thermoplastic temperature and thenplacing the billet into the cavity of the forming mold, the forming moldis heated to be at the suitable thermoplastic temperature, and thepunching heads of the cavity are applied to close the two ends of thebillet, a high-pressure air is further fed into the billet so that thebillet of the metal frame 20 is inflated by a pressure of thehigh-pressure air, hence the concave or convex cross section is formedon the billet. Referring further to FIGS. 4 and 9, the billet of theframe 20 is cut in a cutting means, wherein rest materials of the firstand the second side segments 202, 203 are cut, and then the spacedsection 201 is cut as well so that the billet of the metal frame 20 isseparated into a first pipe 20 a and a second pipe 20 b. In thisembodiment, the expanding portion 204 of the spaced section 201 is cutso that the billet of the metal frame 20 is separated into the firstpipe 20 a and a second pipe 20 b, the first pipe 20 a includes a firstconnecting portion 207 formed in a first cut position thereof, and thesecond pipe 20 b includes a second connecting portion 208 formed in asecond cut position thereof. As shown in FIGS. 4 and 10, the first pipe20 a and the second pipe 20 b are connected together in a connectingmeans, the first side segment 202 of the first pipe 20 a and the secondside segment 203 of the second pipe 20 b are twisted toward the samedirection, then the first connecting portion 207 of the first pipe 20 aand the second connecting portion 208 of the second pipe 20 b areconnected with each and coupled together to obtain the U-shaped metalframe 20. In this embodiment, the first and the second pipes 20 a, 20 binclude an equal diameter or different diameters respectively to beconnected together. As illustrated in FIGS. 11-1 and 11-2, when thefirst and the second connecting portions 207, 208 include the samediameter, the first connecting portion 207 of the first pipe 20 a andthe second connecting portion 208 of the second pipe 20 b are connectedtogether to form a connection therebetween, and then the connection ofthe first and the second connecting portions 207, 208 is welded, then afirst weld head 21 is used to fix the first and the second pipes 20 a,20 b or a connector 22 is fixed to the connection of the first and thesecond connecting portions 207, 208, and the first and the secondconnecting portions 207, 208 are fixed by first screw elements 23individually. Referring to FIGS. 12-1, 12-2, when the first and thesecond connecting portions 207, 208 include different diametersrespectively, the punching head is used to punch a hole with anincreased diameter on the first connecting portion 207 of the first pipe20 a, and the first connecting portion 207 of the first pipe 20 a isfitted with the second connecting portion 208 of the second pipe 20 b,then a fitting position of the first and the second connecting portions207, 208 is welded, thereafter a second weld head 24 is applied to fixthe first and the second pipes 20 a, 20 b together or a second screwelement 25 is screwed into the fitting position of the first and thesecond connecting portions 207, 208. With reference to FIG. 12-3, abonding agent is applied onto the fitting position of the first and thesecond connecting portions 207, 208 so that the first and the secondpipes 20 a, 20 b are adhered together.

As shown in FIGS. 4 and 13, a method for forming an U-shaped metal frame30 in accordance with a second embodiment of the present inventioncomprises the step of providing a metal straight tube in a preparingmeans and a forming means, wherein the straight tube is bend formed in acontinuous curve shape to be a billet of the metal frame 30, the billetincludes a spaced section 301 and a first and a second side segments302, 303, and the spaced section 301 of the billet includes an expandingportion 304 formed thereon by using a high-pressure fluid forming or aheat treating method, the first side segment 302 includes a firstrecessed part 305 formed thereon, and the second side segment 303includes a second recessed part 306 formed thereon. As illustrated inFIGS. 4 and 14, the billet of the frame 30 is cut in a cutting means,wherein rest materials of the first and the second side segments 302,303 are cut, and then the spaced section 301 is cut as well so that thebillet of the metal frame 30 is separated into a first pipe 30 a and asecond pipe 30 b. In this embodiment, a certain position between theexpanding portion 304 of the spaced section 301 and a curved corner ofthe spaced section 301 is cut so that the billet of the metal frame 30is separated into the first pipe 30 a and the second pipe 30 b, and thefirst pipe 30 a includes a first connecting portion 307 formed in afirst cut section thereof, and the second pipe 30 b includes a secondconnecting portion 308 formed in a second cut section thereof. As shownin FIGS. 4 and 15, the first pipe 30 a and the second pipe 30 b includean equal diameter or different diameters respectively and are connectedtogether in a connecting means, wherein the first connecting portion 307of the first pipe 30 a and the second connecting portion 308 of thesecond pipe 30 b are connected with each to obtain the U-shaped metalframe 30.

As shown in FIGS. 4 and 16, a method for forming an U-shaped metal frame40 in accordance with a third embodiment of the present inventioncomprises the step of providing a metal straight tube in a preparingmeans, wherein the straight tube is bend formed in a continuous curveshape to be a billet of the metal frame 40, the billet includes a spacedsection 401 and a first and a second side segments 402, 403. Referringto FIGS. 4 and 17, the billet of the frame 40 is fluid formed or heattreated in a forming means so that on the spaced section 401 and thefirst and the second side segments 402, 403 is formed a concave orconvex cross section individually, wherein the spaced section 401 of thebillet of the frame 40 includes a first recessed part 404 and a secondrecessed part 405 formed thereon, and the first side segment 402includes an expanding portion 406 formed thereon. As illustrated inFIGS. 4 and 18, the billet of the frame 40 is cut in a cutting means,wherein rest materials of the first and the second side segments 402,403 are cut, and then the spaced section 401 is cut as well so that thebillet of the metal frame 40 is separated into a first pipe 40 a and asecond pipe 40 b. In this embodiment, a central portion of the spacedportion 401 is cut into the first pipe 40 a and the second pipe 40 b,and one side of the expanding portion 406 of the first pipe 40 a is cutto eliminate rest material, thus forming a first connecting portion 407,and one side of the second side segment 403 of the second pipe 40 b iscut to eliminate rest material, forming a second connecting portion 408.As shown in FIGS. 4 and 19, the first pipe 40 a and the second pipe 40 binclude an equal diameter or different diameters respectively and areconnected together in a connecting means, wherein the first connectingportion 407 of the first pipe 40 a and the second connecting portion 408of the second pipe 40 b are connected with each to obtain the U-shapedmetal frame 40.

As shown in FIGS. 4 and 20, a method for forming an U-shaped metal frame40 in accordance with a fourth embodiment of the present inventioncomprises the step of providing a metal straight tube in a preparingmeans, wherein the straight tube is bend formed in a continuous curveshape to be a billet of the metal frame 50, the billet includes a spacedsection 501 and a first and a second side segments 502, 503. Referringto FIGS. 4 and 21, the billet of the frame 50 is fluid formed or heattreated in a forming means so that on the spaced section 501 and thefirst and the second side segments 502, 503 is formed a concave orconvex cross section individually, wherein the spaced section 501 of thebillet of the frame 50 includes a first recessed part 504 and a secondrecessed part 505 formed thereon, and the first side segment 502includes a first expanding portion 506 formed thereon, the second sidesegment 503 includes a second expanding portion 507 formed thereon. Asillustrated in FIGS. 4 and 22, the billet of the frame 50 is cut in acutting means, wherein rest materials of the first and the second sidesegments 502, 503 are cut, and then the spaced section 501 is cut aswell so that the billet of the metal frame 50 is separated into a firstpipe 50 a and a second pipe 50 b. In this embodiment, a central portionof the spaced portion 501 is cut into the first pipe 50 a and the secondpipe 50 b, and the first expanding portion 506 of the first pipe 50 aand the second expanding portion 507 of the second pipe 50 b are cut toeliminate rest materials, thus form a first connecting portion 508 onthe first expanding portion 506 and a second connecting portion 509 onthe second expanding portion 507. As shown in FIGS. 4 and 23, the firstpipe 50 a and the second pipe 50 b include an equal diameter ordifferent diameters respectively and are connected together in aconnecting means, wherein the first connecting portion 508 of the firstpipe 50 a and the second connecting portion 509 of the second pipe 50 bare connected with each to obtain the U-shaped metal frame 50.

The invention is not limited to the above embodiment but variousmodifications thereof may be made. It will be understood by thoseskilled in the art that various changes in form and detail may madewithout departing from the scope and spirit of the present invention.

1. A method for forming an U-shaped metal frame comprising: a preparingmeans: bend forming a straight tube in a continuous curve shape to be abillet of the metal frame, and the billet including a spaced section anda first and a second side segments twisted toward opposite directionsindividually; a forming means: placing the billet of the metal frameinto a cavity of a forming mold, and closing two ends of the billet, andthen feeding a high-pressure fluid into the billet so that a concave orconvex cross section is formed on the billet; a cutting means: cuttingthe billet into a first and a second pipes, and the first pipe includinga first connecting portion formed in a first cut position thereof, andthe second pipe including a second connecting portion formed in a secondcut position thereof; a connecting means: twisting the first sidesegment of the first pipe and the second side segment of the second pipetoward the same direction, and connecting the first connecting portionof the first pipe and the second connecting portion of the second pipetogether to obtain the U-shaped metal frame.
 2. The method for formingthe U-shaped metal frame as claimed in claim 1, wherein the straighttube is bent by a tube bending machine to form a continuously curvedbillet in preparing means.
 3. The method for forming the U-shaped metalframe as claimed in claim 1, wherein the forming mold is split along acurved axial line of the billet in the forming means.
 4. The method forforming the U-shaped metal frame as claimed in claim 1, wherein thecavity of the forming mold includes two punching heads disposed on twosides thereof respectively to close the two ends of the billet.
 5. Themethod for forming the U-shaped metal frame as claimed in claim 4,wherein in the forming means, the concave or convex cross section isformed on the billet by using a fluid forming method, the fluid formingmethod includes placing the billet of the metal frame into the cavity ofthe forming mold, and the punching heads of the cavity are used to closethe two ends of the billet, the high-pressure fluid is fed into thebillet directly so that the billet of the metal frame is inflated in thecavity by using a pressure of the high-pressure fluid, and then theconcave or convex cross section is formed on the billet.
 6. The methodfor forming the U-shaped metal frame as claimed in claim 4, wherein inthe forming means, the concave or convex cross section is formed on thebillet by using a heat treating method, the heat treating methodincludes pre-heating the billet of the metal frame to a suitablethermoplastic temperature and then placing the billet into the cavity ofthe forming mold, the forming mold is heated to be at the suitablethermoplastic temperature, and the punching heads of the cavity areapplied to close the two ends of the billet, a high-pressure air isfurther fed into the billet so that the billet of the metal frame isinflated by a pressure of the high-pressure air, hence the concave orconvex cross section is formed on the billet.
 7. The method for formingthe U-shaped metal frame as claimed in claim 1, wherein in the formingmeans, the spaced section of the billet includes an expanding portionformed thereon, the first side segment includes a first recessed partformed thereon, and the second side segment includes a second recessedpart formed thereon.
 8. The method for forming the U-shaped metal frameas claimed in claim 7, wherein in the cutting means, rest materials ofthe first and the second side segments are cut, and the expandingportion of the spaced section is cut so that the billet of the metalframe is separated into the first pipe and a second pipe.
 9. The methodfor forming the U-shaped metal frame as claimed in claim 7, wherein inthe cutting means, rest materials of the first and the second sidesegments are cut, and a certain position between the expanding portionof the spaced section and a curved corner of the spaced section is cutso that the billet of the metal frame is separated into the first pipeand the second pipe.
 10. The method for forming the U-shaped metal frameas claimed in claim 1, wherein in the connecting means, the first andthe second connecting portions include an equal diameter, and the firstconnecting portion of the first pipe and the second connecting portionof the second pipe are connected with each.
 11. The method for formingthe U-shaped metal frame as claimed in claim 10, wherein the firstconnecting portion of the first pipe and the second connecting portionof the second pipe are connected together to form a connectiontherebetween, and then the connection of the first and the secondconnecting portions is welded, thereafter a first weld head is used tofix the first and the second pipes.
 12. The method for forming theU-shaped metal frame as claimed in claim 10, wherein the firstconnecting portion of the first pipe and the second connecting portionof the second pipe are connected together to form a connectiontherebetween, and then a connector is fixed to the connection of thefirst and the second connecting portions, thereafter the first and thesecond connecting portions are fixed by first screw elementsindividually.
 13. The method for forming the U-shaped metal frame asclaimed in claim 1, wherein in the connecting means, the first and thesecond connecting portions include different diameters respectively, andthe first connecting portion of the first pipe and the second connectingportion of the second pipe are connected with each.
 14. The method forforming the U-shaped metal frame as claimed in claim 13, wherein apunching head is used to punch a hole with an increased diameter on thefirst connecting portion of the first pipe, and the first connectingportion of the first pipe is fitted with the second connecting portionof the second pipe, then a fitting position of the first and the secondconnecting portions is welded, thereafter a second weld head is appliedto fix the first and the second pipes together.
 15. The method forforming the U-shaped metal frame as claimed in claim 13, wherein apunching head is used to punch a hole with an increased diameter on thefirst connecting portion of the first pipe, and the first connectingportion of the first pipe is fitted with the second connecting portionof the second pipe, then a second screw element is screwed into thefitting position of the first and the second connecting portions. 16.The method for forming the U-shaped metal frame as claimed in claim 13,wherein a punching head is used to punch a hole with an increaseddiameter on the first connecting portion of the first pipe, and thefirst connecting portion of the first pipe is fitted with the secondconnecting portion of the second pipe, then a bonding agent is appliedonto the fitting position of the first and the second connectingportions so that the first and the second pipes are adhered together.17. The method for forming the U-shaped metal frame as claimed in claim1, wherein in the forming means, the spaced section of the billetincludes a first recessed part and a second recessed part formedthereon, and the first side segment includes an expanding portion formedthereon.
 18. The method for forming the U-shaped metal frame as claimedin claim 17, wherein in the cutting means, a central portion of thespaced portion is cut into the first pipe and the second pipe, and oneside of the expanding portion of the first pipe is cut to eliminate restmaterial, thus forming a first connecting portion, and one side of thesecond side segment of the second pipe is cut to eliminate restmaterial, forming a second connecting portion.
 19. The method forforming the U-shaped metal frame as claimed in claim 1, wherein in theforming means, the spaced section of the billet includes a firstrecessed part and a second recessed part formed thereon, and the firstside segment includes a first expanding portion formed thereon, thesecond side segment includes a second expanding portion formed thereon.20. The method for forming the U-shaped metal frame as claimed in claim19, wherein in the cutting means, a central portion of the spacedportion is cut into the first pipe and the second pipe, and one side ofthe first expanding portion of the first pipe is cut to eliminate restmaterial, thus forming a first connecting portion, and one side of thesecond expanding portion of the second pipe is cut to eliminate restmaterial, forming a second connecting portion.